Well defined choices. Of course you didn't mention that all three options are a lot of work if custom code is required, and the first has the potential to be very fragile.
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MikeSchinkelFeb 10 '11 at 15:33

1

I didn't say any of the three was a walk in the park, lol. ;-)
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Denis de BernardyFeb 10 '11 at 15:46

Are there any handy examples on how to create code using those 3 workarounds mentioned above? I'm trying to build a plugin that relates custom post types and am trying really hard to find a solution, given that I cannot use the Posts2Posts plugin within my own plugin.
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drtanzAug 9 '12 at 16:00

You can create relationships between custom post types with the plugin Sub Posts, price: $ 19.99. With this plugin you're done in minutes, from creating the relationships to displaying them in widgets or shortcodes.